The other bad news is you will need to pay at least $600 a week to the bank for a one-bedroom home.

And, eek, some more bad news* - you'll probably pay more in interest rates than the entire cost of home.

*To be fair, this is not new news. 'Mortgage' comes from Old French, meaning 'death pledge.' People have been paying lots of interest on loans for centuries.

The good news is you could get a flatmate to help pay the mortgage in two- or three-bedroom homes. Another sliver of hope is the Government keeps saying the prices are a cap, not a target, so they could get cheaper if the price of labour and materials drop.

Newshub ran numbers through an extremely helpful mortgage calculator at Sorted.org.nz to figure out how much mortgage you'd be paying on Kiwibuilds. We assumed a 6 percent interest rate.

According to the figures we've run, only households that are wealthier than average will be able to afford KiwiBuild homes.

But the Government has been pretty straight up that KiwiBuild is not about getting low-income New Zealanders into homes - it's about helping out middle class earners who used to be able to afford a home but who now struggle to find something affordable.

We've been generous with the assumed deposit you'll need. At the moment, banks may choose not to loan to first home buyers with a deposit of 10 percent and may require 20 percent instead.

The Government has indicated it may make Welcome Home Loan loans easier to access, so a deposit may become less of a hurdle. Some first home buyers can access the loans at the moment, but many will be stuck in the territory of earning-too-much-for-a-Welcome-Home-loan and not-earning-enough-to-stump-up-a-20-percent-deposit.

To be eligible for a Welcome Home Loan, your income for the last year must have been $85,000 or less if you are the sole borrower. If you are partnering with one or more borrowers to buy a house, then you can have a combined household income up to $130,000.

$650,000 three-bedroom KiwiBuild in Auckland

The deposit: A 10 percent deposit would be $65,000, which, once paid, takes the mortgage to $585,000.

The mortgage: $809 a week for 30 years.

To live comfortably: For the mortgage to make up no more than 30 percent of household costs, owner/s will need to earn $139,706 a year. The average annual combined household income was $100,103 for the year ended June 2017.

For a bank to lend: Economist Gareth Kiernan, chief forecaster at Infometrics, said a bank would give a couple on an income of $90,800 a mortgage for a $650,000 house if they paid a 20 percent deposit. That income would need to be higher if a smaller deposit was paid.

The interest: You will pay $676,789 in interest alone to the bank.

Flatmates: The scenario changes if there's a flatmate or two. If four people lived in the house, two could pay $200 rent each, leaving $406 of mortgage payable a week.

$600,000 two-bedroom KiwiBuild in Auckland

The deposit: You'll need at least a 10 percent deposit of $60,000, taking the mortgage to $540,000.

The mortgage: $747 a week for 30 years.

To live comfortably: Owner/s will need to earn $129,480 a year if the mortgage is to make up 30 percent of their income.

Interest: You will pay $624,728 in interest alone to the bank.

$500,000 one-bedroom KiwiBuild in Auckland or homes outside Auckland

The deposit: You'll need at least a $50,000 deposit and a mortgage of $450,000.

The mortgage: $622 a week for 30 years.

To live comfortably: Owner/s will need to earn $107,813 a year if the mortgage is 30 percent of their income.